wrote:
--------------------------
** Wot a tedious ******..



We already knew it's not the crt at fault. Another poster that
asks and gets the correct answer, but remains entirely lost.


Hogwash.


** Nope - those hogs are not in need of any washing .


I went back and read all the responses to my posts about this
CRT. Most likely the CRT was not at fault but this was not known for
sure. Now I know for sure the CRT is OK. Your reply does nothing to
enlighten anybody. You have not posted anything useful. Why is that?
You posted "Presumably the electrode voltages aren't staying the same
as the thing sweeps across the screen." That's all you posted.



** That is VERY good answer.

Every half decent CRT scope made uses balanced drive to the deflection plates - vertical and horizontal. There is a reason for doing so - it keeps the spot on the screen focussed.

YOU have the darn thing in front of you but are so dopey you cannot say if that is or is not the case with your simple kit scope.

FYI:

When I was 17 and at high school, I saved my pennies and bought all the parts to to make a basic, 2MHz, 5 tube, 3 inch CRT scope.

My brother in law fabricated the steel case as an 18th birthday present - I still have it and it works fine - hence my affection for analogue scopes.

It uses balanced drive for deflection.

The focus is quite good.



..... Phil